Note change of day and location this week only for Van Vleck Lecture -- Refreshments to be served after the colloquium.

The Sudbury Neutrino Observatory (SNO) was a 1,000 tonne heavy-water-based neutrino detector created 2 km underground in an active nickel mine near Sudbury, Canada. SNO studied neutrinos from 8B decay in the Sun by observing one neutrino reaction sensitive only to solar electron neutrinos and others sensitive to all active neutrino flavors. It found clear evidence for neutrino flavor change. This requires modification of the Standard Model for Elementary Particles and confirms solar model calculations with great accuracy. Future measurements at the expanded SNOLAB facility will search for Dark Matter particles thought to make up 26% of our Universe and neutrino-less double beta decay, a rare form of radioactivity that can tell us further fundamental properties of neutrinos. The lecture will provide a brief description of the science of SNO and the status and science to be addressed by SNOLAB experiments.